Field of the Invention
The present invention relates to a heat treatment method and a heat treatment apparatus for applying flash light to a thin plate-like precision electronic substrate (hereinafter, simply referred to as a “substrate”) such as a semiconductor wafer or a glass substrate, in which a high-dielectric-constant gate insulator is formed on a base material such as silicon with an interface layer film sandwiched in between, to heat the high-dielectric-constant gate insulator.
Description of the Background Art
Conventional field-effect transistors (FETs) have commonly used silicon dioxide (SiO2) for their gate insulators, but as the gate insulators become thinner along with downsizing of devices, increasing leakage current is becoming an issue. Thus, use of materials (high dielectric constant materials) having higher dielectric constants than silicon dioxide for gate insulators and development of metal gate electrodes, i.e., use of metals for gate electrodes, are proceeding as disclosed in, for example, US2011/0081753.
However, high-dielectric-constant gate insulators formed by depositing high dielectric constant materials contain a large number of defects such as point defects, and such defects can be a cause of leakage current. Examples of methods for reducing defects in the high-dielectric-constant gate insulators include a method for destroying defects through post-deposition annealing (PDA) and a method for inactivating defects by introduction of nitrogen (nitriding).
Nitriding of a high-dielectric-constant gate insulator is generally required to be conducted at high temperatures. However, a lengthy high-temperature processing time can cause nitriding of even the interface layer film such as silicon dioxide, which is formed as the base of the high-dielectric-constant gate insulator, resulting in degradation in the quality of the interface. Following this, problems arise such as a considerable decrease in the mobility of carriers and an increase in equivalent oxide thickness (EOT).